In order to control a computer numerical control apparatus, robot control apparatus and the like, a man machine controller (MMC) unit becomes necessary for controlling a man-machine communication. For example, an MMC unit connected to a computer numerical control apparatus is allowed to implement an animated simulation operation, interactive program input operation, etc.
A control apparatus or an MMC unit, available for displaying images during such operations, is heretofore provided with display control means therein. The display control means has a processor by itself, wherein an image control signal from a processor of the control apparatus is converted to an image signal, and a resultant image is displayed on a display unit such as a cathode ray tube (CRT), a liquid crystal display (LCD), and the like. The control apparatus also contains transfer control means for transferring input data through operator keys.
When the display control means and the transfer control means are built into a control apparatus, however, the board on which the display control circuit is mounted must be replaced in its entirety when upgrading and changing of the display functions and operational functions are required, whereby cost efficiency and working efficiency are lowered.